The invention relates to valves for installation on liquid inflow pipelines known as adjustable energy dissipating or head loss valves with near zero leakage. The valves to which my invention relates include a fixed plate, an adjustable or mobile plate and a self adjusting taper ring, secured within the valve body between upstream and downstream flanges in the inflow pipeline of various fixed diameters. Further, the valves are suitable for horizontal and vertical mounting orientation in horizontal or vertical pipelines. An example of prior art head loss valve is shown by my related Canadian Patent No. 2,435,724. In this prior art, a simple annular valve body permits the clamping of the valve between opposed pipe flanges with axially extending bolts. The fixed plate is downstream of flow in the liquid inflow pipeline, and is perforated with a pattern of axial holes. The adjustable or mobile plate is upstream of flow in the liquid inflow pipeline, and is likewise perforated and retained within the annular valve body for transverse sliding motion, normal to flow, between a fully opened position where perforations in the fixed and mobile plates are aligned, and a fully closed position where the perforations within the fixed plate are blocked by solid portions of the mobile plate. A further example of prior art head loss valve is shown in U.S. Pat. No. 4,150,693 to Genevey et al. In this prior art valve, the mobile perforated plate is moved between the open and closed position with a manual hand wheel whose rotation meshes with a threaded rod that engages the mobile perforated plate to open and close the valve. The mobile perforated plate is guided in its movement by a housing opposite to the threaded rod, which slides in a slot.
A further example of prior art head loss valve is shown in U.S. Patent Application Publication 2006/0197047 to Batcher et al. This prior art describes a tensioning device capable of reducing fluid leakage between unaligned proximate valve plates. A disadvantage of the prior art valve illustrated in U.S. Pat. No. 4,150,693 is that reverse flow or transient flow conditions acting on the mobile plate can dislodge it from its operating position causing damage, misalignment or disabling of the valve. In addition, the mobile plate shown in U.S. Pat. No. 4,150,693 may vibrate creating noise and potential wear or damage over the long term during bi-directional flow conditions, and such valves without a lower guide or shaft, are not suitable for horizontal mounting in a pipeline. Additionally, the cited prior art does not provide for near zero leakage of the type achieved by those with a Class VI rating established by ANSI/FCI 70-2. Further U.S. Patent Application Publication 2006/0197047 does not provide for a self adjusting tensioning device. The tensioning device must be manually regulated with a tension member.
It is an object of the invention to provide improved sealing of the fixed and mobile plates in a self regulating manner during operation to prevent or substantially prevent leakage during normal flow, reversal of flow and bi-directional transient flow conditions.